A magnetic head for a video or an audio is particularly required to have smoothness on the tape sliding surface and to remove deposits (i.e., attachments) on the head sliding surface. Accordingly, in general, after roughing in the production of a magnetic head, the magnetic head is disposed at a predetermined position and then an abrasive tape is run between two reels with the magnetic head being interposed therebetween to finish a smooth tape-sliding surface of the magnetic head or an abrasive tape is disposed within the cassette to remove the attachments on the sliding surface of the magnetic head. The above-described abrasive tape is produced by providing on a non-magnetic support a fine abrasive particle and a binder or an abrasive particle, a ferromagnetic fine powder and a binder. The abrasive tape has flexibility and therefore, accords with conventional curved shape of the tape-sliding surface of the magnetic head, so that the head surface can be precisely polished and smoothed or the attachments can be removed.
The abrasive layer of the abrasive tape contains a silicon oil or various lubricants as an additive which improve fitting of the abrasive tape to the magnetic head and achieve a good sliding of the same relative to the magnetic head. In this regard, see JP-A-62-92205 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-63-47069 and JP-B-4-22283 (the term "JP-B" as used herein means an "examined Japanese patent publication") describe thereon.
Further, in order to eliminate static electricity which brings about insufficient cleaning or electrostatic adsorption to generate faults on the polishing surface, giving rise to one of causes for obstacles in precisely polishing the magnetic head, an abrasive tape having provided between the abrasive layer and the flexible support thereof an electrically conductive layer has been put into practice. The above abrasive tape is disclosed in JP-A-3-88122 and JP-A-2-106275. JP-A-2-106275 discloses an abrasive tape where an electric conductor layer is provided between the abrasive layer and the substrate.
Further, JP-A-6-139531 discloses a cleaning tape that a Young's modulus of the first cleaning layer as the upper-most layer (corresponding to the abrasive layer of the present invention) is higher than that of the second cleaning layer (corresponding to the interlayer of the present invention) provided under the first cleaning layer, and further it is concretely described in JP-A-6-139531 that the Young's modulus of the second cleaning layer is 300 to 2000 kg/mm.sup.2.
Also, JP-A-6-179174 discloses an abrasive body having a fine particle-containing layer (corresponding to the interlayer of the present invention) between an abrasive layer and a flexible support. However, JP-A-6-179174 has no words as to the Young's modulus though the abrasive body having the interlayer is well-known.
On the other hand, an attempt has been made to improve the abrasive property of the material to be polished by controlling the abutting of the abrasive tape against the material to be polished and JP-B-U-4-45814 (the term "JP-B-U" as used herein means an "examined Japanese utility model publication") discloses an abrasive tape where a buffer resin layer is provided between the abrasive layer and the support and reports that the buffer resin layer is effective in preventing the occurrence of faults due to an excessive pressure applied particularly to a thin material to be polished. Here, the reference does not disclose a magnetic head as the material to be polished.
To the same effect as in JP-B-U-4-45814, JP-A-4-318324 discloses an abrasive tape where a soft resin layer is formed between the abrasive layer and the support and reports that since the magnetic head of the magnetic disk is floated, an appropriate texture can be imparted without generating deep faults on the disk surface.
Now, in recent years, as the magnetic recording is driven into high density recording, the magnetic head used is also required to have a precision shape and more excellent surface properties. Examples of such a magnetic head include heads having a narrow width for high density recording, such as a thin film head, an amorphous head, a laminate head, an MIG head and an MR head. More specifically, in processing such a magnetic head, roughing at an initial stage and finishing at a final stage are conducted, but if the precision polishing as described above is required, adhesion of an organic material eluted from the abrasive layer or alteration of the layer to be polished by itself may occur to impair the magnetic properties of the magnetic head. If the adhesion of the organic material is eliminated strongly, an antinomic problem arises that the magnetic head is excessively polished and as a result, the effective depth is reduced. In the case of a video head, the effective depth is usually from 10 to 30 .mu.m. If the effective depth is lost, the spacing loss increases to cause reduction in the output.
In order to overcome these problems, it seems to be effective to produce an abrasive tape according to the above-described technique by providing an electrically conductive layer or a resin layer on a non-magnetic support and providing thereon an abrasive layer, however, if the conventional technique is applied as it is, it is very difficult for the abrasive tape obtained to polish a thin film head or a narrower head such as an amorphous head, a laminate head, an MIG head and an MR head in a short period of time to obtain smoothness or a desired shape without undergoing any alteration, or to polish for removing the attachments on the magnetic head in a short time while not reducing so much the effective depth and smooth the head shape to improve the output.